UPDATE: According to AAP manager, Shell V-Power Complete Fuel System Cleaner is being discontinued. I just bought up what the store had left remaining(a case worth) and that's good for 5 years worth of once/twice a year cleanings on all of our vehicles.
Buy it while you can, look for good deals at places like AAP. Not sure, but I remember seeing it on sale elsewhere as well.
Not as an every fill up additive but once every 5-7.5k miles is a good range for this product, if you are using something like MMO every tank or so.